How dangerous is the flu virus to the brain?

The flu virus makes you sluggish, and in severe cases can cause encephalitis, leading to death.

The flu virus makes you feel unwell. (Source: Pixabay)

The flu epidemic is raging across East Asia. Many countries such as Japan, South Korea, China... have recorded the most serious seasonal flu epidemic in many years, causing hospitals to be overloaded and medicine to be scarce.

In Vietnam, the Ministry of Health recorded a local increase in flu cases from the end of 2024 and Tet, but did not increase dramatically compared to previous years. The main causes were A/H3N2, A/H1N1 and influenza B viruses.

As flu cases increase, it is important to be aware of how the virus can impact certain aspects of your health. Mild symptoms of the flu include fever, body aches, headache, cough, sore throat, and fatigue.

However, research shows that the flu can also impact the brain, leading to short-term problems like brain fog, mood swings and sluggishness.

In some cases, it can also cause persistent neuroinflammation that impairs cognitive function and memory.

Why does the flu make us feel sluggish?

Scientists have discovered that a group of nerve cells in the throat infected with the flu virus sends signals to the brain, causing symptoms such as fatigue, loss of appetite and sluggishness.

A study published in the journal Nature explains that infections lead to the production of chemicals called prostaglandins, which help the body fight disease but also make you feel unwell.

Scientists found that these chemicals do not need to travel to the brain through the bloodstream. Instead, nerve cells in the throat detect them directly and send signals to the brain.

The deadly effects of flu on the brain

In rare cases, the flu virus can invade the brain and cause a serious condition called influenza-associated encephalitis (IAE), which can lead to severe symptoms or even death.

A new study from Osaka University (Japan) found that the virus enters the brain through endothelial cells, which form a protective barrier between the blood and the brain. Once inside, the virus does not multiply but accumulates viral proteins, damaging the brain's defense system.

The researchers found that conventional antiviral drugs that block viral growth may not work for IAE. However, drugs that block viral protein production have shown promising results in mice, reducing brain damage and improving survival rates.

The lingering effects of flu on the brain

A study from the University of Michigan (USA) found that people hospitalized with severe flu may face a higher risk of long-term brain damage than those hospitalized with Covid-19.

Research shows that patients hospitalized with flu are twice as likely to need treatment for neurological problems as those hospitalized with Covid-19.

This included a 44% increased risk of nerve pain, a 35% higher risk of battling persistent migraines, and a 10% higher risk of stroke or dementia.

The cause may be due to inflammation spreading throughout the body, damaging blood vessels.

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